Four-Way Diesel Catalysts and Methods of Use

A method of treating a lean burn diesel exhaust gas stream including CO, hydrocarbons, NOx and soot comprising flowing exhaust from a diesel engine through a wall flow filter having a plurality of longitudinally extending passages formed by longitudinally extending porous walls bounding and defining the passages and an axial length extending between an inlet end and an outlet end wherein the passages comprise inlet passages open at the inlet end and closed at the outlet end, and outlet passages being closed at the inlet end and open at the outlet end, the exhaust gas stream contacting an SCR catalyst composition disposed within the porous walls and subsequently contacting the exhaust gas stream with an oxidation catalyst disposed on the walls of the outlet passages extending from the outlet end and less than the axial length of the wall flow filter.

A method of treating an exhaust gas stream including CO, hydrocarbons, NOx and soot comprising passing the exhaust gas stream through a single catalytic article comprising a wall flow filter having an inlet end, an outlet end and an axial length, the wall flow filter including a first region extending the entire axial length that removes substantially all of the NOx in the exhaust stream and a second region extending from the outlet end of the wall flow filter less than the axial length for oxidizing one or more of CO, hydrocarbons or soot.

A catalyst article for treating an exhaust stream comprising CO, hydrocarbons, NOx and soot, the catalyst article comprising a wall flow filter having an inlet end, an outlet end and an axial length, the wall flow filter including a first region extending the entire axial length and a second region extending from the outlet end of the wall flow filter for less than the axial length, the first region effective to remove substantially all of the NOx in the exhaust stream and the second region effective to oxidize one or more of the CO, hydrocarbons and soot.